Amazon reptiles

Anacondas and other scaled wonders of the rainforest

A majority of the world’s reptiles are found in the tropics, including tropical South America. But despite this abundance of species, our knowledge of many Amazon reptiles is still poor.

While we know that some reptile groups are particularly diverse, others occur in low densities compared to similar areas in the Asian tropics. For example, turtles, tortoises and venomous snakes are poorly represented when compared to many other humid tropical areas of the world.

Amazon reptiles occupy a very wide range of habitats (e.g. creeks, oxbows, rainforest canopy) and also show differences in their feeding habits.

Most reptiles, such as the boa, are carnivorous (they feed exclusively on other animals) while others, such as the green iguana, are primarily herbivorous (they eat mostly plant matter).1

Boas are collectively referred to as boines in South America, and they are without doubt the most famous snakes in the world. The widespread boine fauna of the Amazon River Basin and the Guianas includes five species, namely the boa constrictor (Boa constrictor), the emerald tree boa (Corallus caninus), the common tree boa (C. enydris), the rainbow boa (Epicrates cenchria) and the green anaconda (Eunectes murinus).

These species have overlapping distributions on the South American mainland, and often occur with overlapping ranges.

Boas occur in a variety of habitats – from dry areas with low rainfall to lush rainforests - except for the emerald tree boa, only found in lowland tropical rainforests.

To kill their prey, boas lie in wait until a suitable prey is in sight, wrap themselves around the victim and suffocate them. Prey may include fish, turtles, lizards, crocodiles, birds and even mammals, including deer.

Snakes need to swallow their prey whole. A large snake such as the boa can eat a 210 gr roof rat or a 9kg capybara. Different boa species use different habitats (e.g. trees, rivers), and by each specializing on different prey, they are able to co-exist with limited competition from each other.

Crocodiles and alligators (caimans)

Most active at night, these animals eat fish and other water dwelling animals, such as capybaras, birds and snakes.

True crocodilians and alligators/caimans look the same, but “crocs” have snouts that are more pointed than the “gators”. Crocodiles also have the upper fourth tooth visible when the jaws are closed. Alligators/caimans avoid saltwater. They are also more abundant.

Turtles

Turtles found in the Amazon River Basin belong to an ancient group called side-necked turtles. The head is tucked sideways rather than being hidden inside the shell. Only about 20 species are found.

The South American river turtle (Podocnemis expansa), also known as arrau and charapa, is the largest freshwater turtle in South America, with shells over 80 cm long reported for some females. Males are smaller and measure 40 cm on average.

These turtles have inhabited the earth for more than 158 million years and have a wide distribution. The species can be found in the Amazon and Orinoco river basins in Venezuela, Ecuador, Colombia, Peru, Bolivia, Brazil and Guyana.

Plight of the turtle

South American river turtles are of biological, social and cultural importance. Biologically, turtles act as indicator species as they are sensitive to changes to their habitat.

According to the Colombian Red Data Book of Reptiles, the species is in critical danger of extinction in the Orinoco while in the Amazon it has been classified as endangered. In both regions, its threat status is a result of hunting pressures.

Fishers irreparably disturb the sandy shores where turtles lay their eggs by spreading out their fishing lines and nets, lighting fires and creating noise with outboard motors.

Riverside communities will also go on outings along the sandy river banks to capture turtles, roast their meat and eat their eggs, not only putting an end to the adult female’s life, but also destroying the nests.

But there are good news from Peru. There, riverside indigenous communities are collecting eggs in order to release them in safety. These are encouraging early footsteps in sustainable management of the species.